increaseing active return will cause the std dev of active return to increase at a greater ratio than 1 for 1, so when looking at IR only, active indexing will be superior even though full blown active management will produce a higher alpha
No, it’s just not exponentially increased - it couldbe a linear increase in alpha with tracking risk and would still decrease the IR (Think alpha is at 2 with active ret at 1 and tracking risk at 0.5, increase alpha to 1.5/1 and you have less than two).